Did you know that the Holland Tunnel was once the longest underwater tunnel in the world?
Spanning 8,557 feet beneath the Hudson River, the Holland Tunnel became the longest tunnel in the world upon its completion in 1927. One of several highway channels beneath the river, the tunnel connects Lower Manhattan's Canal Street with Jersey City, New Jersey.
Planning for a trans-river crossing was initiated in 1906 by a joint commission between New York and New Jersey. At the time, the Hudson River ferries were severely overburdened, carrying an average of 30 million cars and trucks per year.
The original plan was to reduce strain on the ferries by building a bridge. But with a bridge came overwhelming construction costs and a need for excessive amounts of land to build accessways. Eventually, the planners abandoned the idea in favor of a tunnel.
Throughout the next several years, a series of tunnel designs were considered -- including a proposal by George Goethals, for whom a bridge connecting Staten Island to New Jersey is named. Ultimately, planners selected an innovative design by engineer Clifford Milburn Holland, which called for two separate tunnel tubes that each would contain two lanes of traffic, both flowing in the same direction.
With Holland as chief engineer, work on the "Hudson River Vehicular Tunnel Project" commenced in October 12, 1920, as workers on both the New Jersey and Manhattan sides simultaneously tunneled towards the center of the river. In 1924, just one day before the two sides were scheduled to meet, Holland died at the age of 41 from complications during a tonsillectomy. He was replaced by engineer Milton H. Freeman, who also died after just several months on the project. Freeman was succeeded by Ole Singstad, who ultimately saw the tunnel to completion.
Singstad is credited for the tunnel's revolutionary ventilation system. After an estimated 2,000 tests to determine the amount of exhaust gases that would be produced by vehicles traveling through the tunnel and the ultimate effect on drivers, the engineering team developed an automatic two-duct system, which uses one duct to pull in fresh air and the other to dispel exhaust.
To ensure that enough clean air is maintained in the tunnel, the team implemented a network of 42 intake fans and 42 exhaust fans. (Only 56 of the 84 are in operation at all times. The other 28 are reserved for emergencies.) The new system made the Holland Tunnel the world's first major ventilated highway tunnel and became the model for other underwater tunnels in New York City and around the world.
After nearly seven years of construction, the Holland Tunnel officially opened at midnight on November 13, 1927, adorned with 3.1 million new ceiling tiles and 2.9 million wall tiles. On its first day of operation, 51,694 vehicles passed through the tunnel, the first of which was a truck making a shipment to Bloomingdale's Department Store in Manhattan.
In 1931, the tunnel was adopted by the Port Authority of New York and New Jersey, which continues to operate it today. Considered an outstanding engineering achievement, the tunnel was granted National Historic Civil and Mechanical Engineering Landmark status in 1984.